<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
    /* css reset */
    *{
        margin: 0;
        padding: 0;
    }
    body,html{
        height: 100%;
    }
    body{
        /* 手机网页 apple-system */
        /* css继承 */
        font-family: -apple-system-font,  sans-serif;
        background-color: #111;
    }
    .page{
        position: absolute;/* 格式化上下文 绝对定位 脱离了文档流*/
        top: 0;
        right: 0;
        bottom: 0;
        left: 0;
        overflow-y: auto;/*内部滚动*/
        -webkit-overflow-scrolling: touch;/*让我的滚动如丝般顺滑*/
    }
    .page__hd{
        height: 200vh;/*相对单位，相对于viewport（视窗）的单位*/
    }
    </style>
</head>
<body>
    <div class="page">
        <div class="page__hd">
            <div class="page__title">Flex</div>
            <div class="page__desc">Flex布局</div>
        </div>
        <!-- BEM -->
        <div class="page_bd padding__bd_spacing">
            <!-- weui 项目前缀，弹性布局组件 新一轮的BEM-->
            <div class="weui-flex">
                <div class="weui-flex__item">
                    <div class="placeholder">weui</div>
                </div>
            </div>
        </div>
    </div>
</body>
</html>